diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -620,6 +620,11 @@
   bool canCreateUndefOrPoison(const Operator *Op);
   bool canCreatePoison(const Operator *Op);
 
+  /// Return true if V is poison given that ValAssumedPoison is already poison.
+  /// For example, if ValAssumedPoison is `icmp X, 10` and V is `icmp X, 5`,
+  /// impliesPoison returns true.
+  bool impliesPoison(const Value *ValAssumedPoison, const Value *V);
+
   /// Return true if this function can prove that V does not have undef bits
   /// and is never poison. If V is an aggregate value or vector, check whether
   /// all elements (except padding) are not undef or poison.
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4808,6 +4808,64 @@
   return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/true);
 }
 
+bool llvm::impliesPoison(const Value *ValAssumedPoison, const Value *V) {
+  // Construct a set of values which are known to be poison from the knowledge
+  // that ValAssumedPoison is poison.
+  SmallPtrSet<const Value *, 4> PoisonValues;
+  PoisonValues.insert(ValAssumedPoison);
+  const Instruction *PoisonI = dyn_cast<Instruction>(ValAssumedPoison);
+  unsigned Depth = 0;
+  const unsigned MaxDepth = 2;
+
+  while (PoisonI && Depth < MaxDepth) {
+    // We'd like to know whether an operand of PoisonI is also poison.
+    if (canCreatePoison(cast<Operator>(PoisonI)))
+      // PoisonI can be a poison-generating instruction, so don't look further
+      break;
+
+    const Value *NextVal = nullptr;
+    bool MoreThanOneCandidate = false;
+    // See which operand can be poison
+    for (const auto &Op : PoisonI->operands()) {
+      if (!isGuaranteedNotToBeUndefOrPoison(Op.get())) {
+        // Op can be poison.
+        if (NextVal) {
+          // There is more than one operand that can make PoisonI poison.
+          MoreThanOneCandidate = true;
+          break;
+        }
+        NextVal = Op.get();
+      }
+    }
+
+    if (NextVal == nullptr) {
+      // All operands are non-poison, so PoisonI cannot be poison.
+      // Since assumption is false, return true
+      return true;
+    } else if (MoreThanOneCandidate)
+      break;
+
+    Depth++;
+    PoisonValues.insert(NextVal);
+    PoisonI = dyn_cast<Instruction>(NextVal);
+  }
+
+  if (PoisonValues.contains(V))
+    return true;
+
+  // Let's look one level further, by seeing its arguments if I was an
+  // instruction.
+  // This happens when I is e.g. 'icmp X, const' where X is in PoisonValues.
+  const auto *I = dyn_cast<Instruction>(V);
+  if (I && propagatesPoison(cast<Operator>(I))) {
+    for (const auto &Op : I->operands())
+      if (PoisonValues.count(Op.get()))
+        return true;
+  }
+
+  return false;
+}
+
 static bool programUndefinedIfUndefOrPoison(const Value *V,
                                             bool PoisonOnly);
 
diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -695,6 +695,59 @@
   EXPECT_EQ(ComputeNumSignBits(A, M->getDataLayout()), 1u);
 }
 
+TEST_F(ValueTrackingTest, impliesPoisonTest_Identity) {
+  parseAssembly("define void @test(i32 %x, i32 %y) {\n"
+                "  %A = add i32 %x, %y\n"
+                "  ret void\n"
+                "}");
+  EXPECT_TRUE(impliesPoison(A, A));
+}
+
+TEST_F(ValueTrackingTest, impliesPoisonTest_ICmp) {
+  parseAssembly("define void @test(i32 %x) {\n"
+                "  %A2 = icmp eq i32 %x, 0\n"
+                "  %A = icmp eq i32 %x, 1\n"
+                "  ret void\n"
+                "}");
+  EXPECT_TRUE(impliesPoison(A2, A));
+}
+
+TEST_F(ValueTrackingTest, impliesPoisonTest_ICmpUnknown) {
+  parseAssembly("define void @test(i32 %x, i32 %y) {\n"
+                "  %A2 = icmp eq i32 %x, %y\n"
+                "  %A = icmp eq i32 %x, 1\n"
+                "  ret void\n"
+                "}");
+  EXPECT_FALSE(impliesPoison(A2, A));
+}
+
+TEST_F(ValueTrackingTest, impliesPoisonTest_AddNswOkay) {
+  parseAssembly("define void @test(i32 %x) {\n"
+                "  %A2 = add nsw i32 %x, 1\n"
+                "  %A = add i32 %A2, 1\n"
+                "  ret void\n"
+                "}");
+  EXPECT_TRUE(impliesPoison(A2, A));
+}
+
+TEST_F(ValueTrackingTest, impliesPoisonTest_AddNswOkay2) {
+  parseAssembly("define void @test(i32 %x) {\n"
+                "  %A2 = add i32 %x, 1\n"
+                "  %A = add nsw i32 %A2, 1\n"
+                "  ret void\n"
+                "}");
+  EXPECT_TRUE(impliesPoison(A2, A));
+}
+
+TEST_F(ValueTrackingTest, impliesPoisonTest_AddNsw) {
+  parseAssembly("define void @test(i32 %x) {\n"
+                "  %A2 = add nsw i32 %x, 1\n"
+                "  %A = add i32 %x, 1\n"
+                "  ret void\n"
+                "}");
+  EXPECT_FALSE(impliesPoison(A2, A));
+}
+
 TEST_F(ValueTrackingTest, ComputeNumSignBits_Shuffle_Pointers) {
   parseAssembly(
       "define <2 x i32*> @test(<2 x i32*> %x) {\n"